Rates of posttraumatic stress disorder (PTSD) are high among combat Veterans. Estimates of PTSD within Iraq and Afghanistan Veterans suggest that nearly 17% of active duty and over 24% of reserve service members screen positive for PTSD. Among individuals diagnosed with PTSD, the incidence of drug abuse and addiction is markedly elevated, with the highest comorbidity observed for alcohol use disorders, estimated to be as high as 85% in individuals seeking PTSD treatment. When these comorbidities manifest they result in poorer psychological, functional, and treatment outcomes than either disorder alone. Evidence suggests that neurobiological mechanisms, such as dysregulation of specific brain structures (e.g., amygdala, insula, prefrontal cortex, and striatum) appear to play crucial roles in the maintenance and remission of concurrent AD/PTSD. Currently there are no translational imaging studies that have examined whether patterns of brain activation can predict differences in treatment response in this population, and no attempts have been made to link psychotherapeutic interventions to neurobiological targets in AD/PTSD individuals. Therefore, the long- term goal of this line of research is to use neuroimaging tools to advance our ability to provide optimized, targeted interventions that support improved outcomes for Veterans with AD/PTSD. The objective of this proposal, which is a first step in pursuit of this goal, is to measure the brain response to an anticipatory task and an alcohol cue reactivity task before and after treatment for AD/PTSD in order to 1) delineate a neural profile of treatment responsiveness to empirically supported interventions, and 2) to compare the relative effects of an exposure based to a non-exposure based treatment on the neural substrates thought to maintain these disorders. Participants will receive one of two, 8-week-long, treatments within an ongoing, VA-funded, randomized controlled trial designed to compare the effectiveness of an exposure-based psychotherapy (i.e., Concurrent Treatment of PTSD and Substance Use Disorders Using Prolonged Exposure (COPE)) against the widely used psychotherapy, Seeking Safety (SS), that does not include exposure for the treatment of AD/PTSD. We hypothesize that baseline patterns of brain response will relate to the capacity to improve in the context of therapy, and that the sub-components of COPE and SS will differentially affect change in those neural circuits maintaining AD/PTSD.